The invention relates to high- or medium-voltage switches, and more particularly to switching points for such switches.
Switches for high- or medium-voltage level have mechanical connectors or mechanical disconnectors with an arc duration of at most a few hundred microseconds.
Such a switching point is described in the prior European Patent Application File Reference 99810596.9.
The switching point in a high- or medium-voltage switch contains two fixed contact members, which are cylindrical and, inserted coaxially into one another, form an annular gap. A moving, bridging contact member in the form of a contact ring is fit in the annular gap when the switching point is closed. Coils of an electrodynamic drive are arranged on both sides of the contact ring, in order to move the contact ring in the axial direction.
In order to open the switching point, a current is fed into one of the two coils. Eddy currents are induced in the contact ring, and are essentially in the opposite direction to the current in the coil. The coil and contact ring are thus forced apart from one another, which leads to a translational acceleration of the contact ring, and thus to opening of the switching point.
In order to close the switching point, the current is fed into the other of the two coils, in response to which the contact ring moves back to the original position again, and the switching point is thus closed once again.
An object of the invention is to provide a switching point of the type mentioned initially, which can be opened and closed quickly and with little energy being required.
When the switching point is closed, a bridging contact member in the form of a disk short-circuits two fixed contact members in the rated current direction. The bridging contact member is arranged such that it can rotate about its own center axis, running at right angles to the rated current direction. The eddy currents which are required to form a couple for an electrodynamic rotary contact drive are induced in the moving bridging contact member.
The energy which needs to be applied to rotate the bridging contact member is less than for contact members which move in translation, in comparable switching points. The energy required for opening and closing the switching point is thus reduced.
The switching point with the rotating contact member can be utilized more optimally dielectrically, since the fixed contact members can be designed to be rounder than in the case of switching points with contact members which move in translation.
During opening, two contact gaps are formed, each of which is bridged by one of two arc elements, which are in series. This connection of arc elements in series increases the arc voltage dropped across a contact arrangement of the switching point, which in turn allows commutation particularly quickly and effectively when there is a susceptible parallel path.